ABSTRACT
Constructed wetlands technology is emerging as a low-cost, easily operated efficient alternative to conventional treatment systems for a wide variety of wastewaters. This chapter summarizes information on performance expectations and loading rates and presents an overview of parameters normally regulated, loading factors for existing systems, and information on reaction kinetics. Information is segregated for the two types of systems: conventional surface flow systems with an exposed free water surface and the more recent subsurface flow systems with water levels below the surface of a permeable substrate. Wetland systems reduce many contaminants, including biochemical oxygen demand, suspended solids, nitrogen, phosphorus, trace metals, trace organics, and pathogens. This reduction is accomplished by diverse treatment mechanisms: sedimentation, filtration, chemical precipitation and adsorption, microbial interactions, and uptake by vegetation. Information is generally available on only two waste types: municipal and mining wastewaters.
